CMR versus CCTA with fractional flow reserve for diagnosing obstructive coronary artery disease in higher risk patients: rationale and design of CONCORD - a prospective, single-centre diagnostic accuracy study.

Background: In patients with suspected coronary artery disease (CAD), the optimal diagnostic algorithm remains uncertain. Non-invasive imaging plays a central role as a "gatekeeper" to invasive coronary angiography, with both cardiovascular magnetic resonance (CMR) and coronary computed tomography angiography (CCTA) with fractional flow reserve (FFR_CT) proving effective in reducing unnecessary invasive procedures. However, direct comparisons between the two modalities are limited.

Trial design: CONCORD is a prospective, single-centre study comparing the diagnostic accuracy of CMR and CCTA/FFR_CT to detect obstructive CAD in 300 patients with suspected angina referred for clinically indicated invasive coronary angiography. The primary outcome is the diagnostic accuracy of each imaging protocol against the reference standard of invasive fractional flow reserve. Key secondary outcomes include whether quantitative CMR is more accurate than qualitative CMR and/or CCTA/FFR_CT, and whether hybrid imaging models may outperform single modality strategies (NCT04761991).

Summary: CONCORD will comprehensively evaluate two frontline non-invasive functional imaging modalities in patients with suspected angina and determine the comparative accuracy of CCTA/FFR_CT and CMR in patients with a moderate-high risk of CAD. Evaluation of these strategies has the potential to inform both the quality and cost-effectiveness of imaging services.